The U.S. Navy plays a vital role in deterring nuclear aggression with its fleet of ballistic missile submarines. Because the subs can't be targeted when submerged, they are the most survivable component of the nation's strategic deterrent. Being able to survive an attack and then retaliate appropriately is what makes a deterrent credible to enemies.

As overseas missile threats spread and diversify though, another part of the Navy is becoming increasingly important to deterring the use of nuclear weapons -- or dealing with the consequences when deterrence fails. That is the sea-based air and missile defense system known as Aegis.

The Navy traditionally hasn't thought about its Aegis destroyers and cruisers as strategic weapons, but they contribute to nuclear deterrence in many ways, from detection and tracking of threats to interception of incoming missiles to cueing of other defensive systems. All of these features can potentially dissuade an aggressor from launching because they raise doubts about the ability of enemy weapons to hit intended targets.

If deterrence nonetheless fails, Aegis might become more important to national survival than all the warheads in the nuclear arsenal. The combination of networked sensors, agile long-range missiles and automated fire control comprising the core of Aegis can destroy a vast array of airborne and ballistic threats long before they reach U.S. territory, or allied nations, or U.S. forces stationed abroad.

The USS Sampson, an Aegis destroyer launched in 2006 from the Bath Iron Works in Maine. The flat panels below the bridge house a six-megawatt radar.

Wikipedia

That is just the beginning. Because Aegis is mobile at sea, it is much harder for enemies to preempt in wartime than fixed defenses on land would be. Because it is the only sea-based ballistic missile defense system in the world, several allies have bought it too. And because on-going modernization initiatives will link together all relevant warfighting assets including those in orbit, the defensive potential of each Aegis warship will be multiplied far beyond what was feasible only a few years ago.

So the Navy was prescient when it named Aegis after the shield of Zeus in Greek mythology because it is on its way to becoming the centerpiece of the only global missile defense system ever created.

Unfortunately, this trend is being driven by the aforementioned spread of threats, which compels the Navy to cope with worrisome innovations like maneuvering ballistic warheads and low-flying, long-range cruise missiles. So a system originally devised to defend mainly against manned aircraft and anti-ship missiles will now need to deal with a lot of other threats too.

That includes intercontinental ballistic missiles. Although the Obama Administration canceled a program to equip Aegis with interceptor missiles that could match ICBM speeds, the Navy has determined that missiles now joining the force have some capacity to engage long-range ballistic warheads. Aegis can track most ballistic missiles (including ICBMs) in the initial phase of their trajectories and then intercept warheads when they are released -- regardless of whether those missiles launch on land or at sea.

The Trump Administration's recently completed missile defense review will likely restart the effort to provide Aegis with a new generation of interceptors designed to destroy even the longest-range ICBMs. Teamed with the Ground-Based Midcourse Defense (GMD) system already deployed on the U.S. West Coast, Aegis could become part of a layered homeland defense capable of negating over 90% of the warheads in a nuclear attack.

I should mention at this point that Lockheed Martin and Raytheon, the most important players on Aegis, both contribute to my think tank -- as does Boeing, prime contractor on GMD. Lockheed is also a consulting client. As a longtime skeptic about the durability of nuclear deterrence, I have a soft spot in my heart for any company involved in providing a defensive alternative in the event deterrence fails.

Aegis has now entered what prime-contractor Lockheed Martin refers to as the third generation of its missile defense evolution, in which each warship eventually will be able to perform air and missile defense simultaneously, and engage hostile warheads relying on inputs from remote sensors -- in some cases, hundreds of miles away. There are currently three dozen warships in the U.S. fleet equipped with Aegis anti-missile capabilities, a number that is expected to grow steadily.

Because Aegis is by far the most advanced solution to the threat posed by agile overhead attackers, it is being deployed on land as well as at sea. That trend began when the Obama Administration substituted Aegis technology for GMD hardware that the Bush Administration had been planning to deploy in Europe. Now Japan, worried about North Korea's missiles, is moving forward with its own "Aegis Ashore" installations to complement Aegis warships in its naval fleet.

Lockheed Martin recently won a contract to supply radars for the Japanese land-based installations -- two of which can cover all of the four home islands. Raytheon, which builds the Standard Missiles used as interceptors in the Aegis system, previously won a U.S. Navy contract to develop the next generation of at-sea Aegis radars -- which Lockheed Martin will install. Meanwhile, Lockheed Martin is upgrading radars and other gear on existing Aegis destroyers to the latest "Baseline 9" level of capability.

Collectively, the two companies largely define state of the art in missile defense. The irony of their relationship is that although they fight tooth and nail for each new contract, the success of Aegis has depended on their ability to cooperate in a shared architecture. The Navy has leveraged the competitive dynamic between the two companies to achieve great success in system performance and price stability.

The larger strategic picture into which Aegis fits, though, is what matters most. New airborne and ballistic threats are spreading around the world, threatening America's security and the supremacy of its military forces. Nuclear deterrence remains the foundation of national security strategy, but there is no guarantee it will last indefinitely. In this kind of environment, the Navy's Aegis system is essential to our nation's long-term survival -- not just to strengthen deterrence, but to cope with the consequences if it fails.

The Navy has done a good job of evolving its Aegis franchise to stay current with emerging threats. Given the importance of Aegis, though, the Navy needs to make sure it continues introducing new technology into the fleet at a reasonable pace. Without a modernized, robust Aegis architecture, America and its allies could suffer devastation far beyond what many observers can even imagine.